Recent advances in non-linear optical polymers make them extremely promising materials for high performance optical modulators. Electro-optic coefficients as high as r33=300 pm/V have been demonstrated, and polymer based modulators with high reliability have been made commercially available. These advances have been enhanced by novel device design. In particular silicon waveguides with a narrow slot in the middle, so called slot waveguides (SWG), have been shown to yield high confinement of the optical field inside the slot. The same structures also allow dropping the entire radio-frequency (RF) driving voltage across the narrow slot, thus yielding very high RF E-fields with high optical overlaps. This allows modulators with ultra low drive voltages to be realized.
Vπ is the voltage required to induce TE phase shift between the two arms of the modulator. The definition of Vπ, has been adjusted to be consistent with the nomenclature used herein. A low Vπ has several advantages such as reduced transmitter (Tx) power-consumption in digital data-communication links. It is particularly attractive in the context of optical analog links, where it translates directly into enhanced noise figures since the electrical-to-electrical power gain and the noise factor of the link scale respectively as Vπ−2 and Vπ2. Analog links are receiving a lot of attention for their application in radar remoting and phased arrays and the availability of low noise optical analog links is predicted to have a tremendous impact on this field.
It has been recognized early on that electro-optic polymers constitute a promising material for low Vπ modulators. Low drive voltage modulators have also motivated a considerable amount of research in the lithium niobate community, with Vπ as low as 1.1 V and 1.35 V at respectively 12 GHz and 18 GHz demonstrated with commercially available high bandwidth modulators targeted towards analog optical links. High-speed (>10 GHz) modulators in silicon have also been a very active field in the last decade, and recently important progress has been made towards low voltage modulation with the demonstration of a Vπ of 2 V.
Known in the prior art is Hochberg et al., U.S. Pat. No. 7,200,308, issued Apr. 3, 2007, which is said to disclose systems and methods for manipulating light with high index contrast waveguides clad with substances having that exhibit large nonlinear electro-optic constants χ2 and χ3. Waveguides fabricated on SOI wafers and clad with electro-optic polymers are described. Embodiments of waveguides having slots, electrical contacts, and input waveguide couplers are discussed. Waveguides having closed loop structures (such as rings and ovals) as well as linear or serpentine waveguides, are described. Optical signal processing methods, such as optical rectification and optical modulation, are disclosed.
There is a need for improved optical modulation systems and methods.